(CNN) -- Those probably were not UFOs that hovered over China recently, a Massachusetts Institute of Technology analyst said.

The images of the UFOs have caused quite a stir in China and on blogs around the world.

But many of the images appear to be faked with the software program Photoshop and the ones that were not faked seem to depict the launch of a Chinese ballistic missile, said Geoffrey Forden, an MIT weapons analyst.

Forden, who also specializes in Russian and Chinese space systems, published his analysis on a blog called "Arms Control Wonk."

In the analysis, Forden used scientific theories to examine the images of the flying object that he felt were not created with Photoshop.

"It seems to me that a DF-21 (missile) launch somewhere near Jiuquan and aimed at a point somewhere in the eastern Gobi desert is the most likely cause of this 'UFO'", Forden wrote.

Chinese officials have been looking into the reports about UFOs. They have said they were trying to determine whether the objects were private or military aircraft, rocket flares, reflection in the sky or something else.

The first sighting occurred at Hangzhou's Xiaoshan Airport, in the eastern part of the country, according to the state-controlled Xinhua news agency.

Eighteen flights were delayed or rerouted and operations shut down after twinkling lights were spotted above the terminal around 9 p.m. July 7, the agency said. According to Xinhua, speculation has centered on a private aircraft. The state-run China Daily quoted a source saying the object had a military connection.

Purported photos of the unworldly object have appeared online, on YouTube and on television news shows.

Meanwhile, The Shanghai Daily reported a UFO appeared above the city of Chongqing a day later.